The present invention relates to preparation of a composition containing a dehydrated food composition and live probiotic lactic acid bacteria and particularly to dehydration, and more particularly to dehydration by spray-drying, of a probiotic lactic acid bacteria culture and a food composition for preparation of the dehydrated composition.
The subject of the invention is a new process for the preparation of a dehydrated food composition containing live lactic acid bacteria.
To dry lactic acid bacteria, industry needs to have available processes which are easy to use and which are economical. Spray-drying generally consists in spraying a suspension of lactic acid bacteria in a vessel and under a stream of hot air, the vessel comprising, to this effect, a hot air inlet, an outlet for discharging the air and an outlet for recovering the powder of dried lactic acid bacteria.
U.S. Pat. No. 3,897,307 (Porubcan et al.) describes a process for the preparation of a dehydrated milk-containing food composition comprising live lactic acid bacteria. In this process, the milk is fermented by lactic acid bacteria, ascorbic acid and sodium glutamate are added thereto and then the fermented milk is spray-dried under a stream of hot air. Other methods of preparation of spray-dried fermented milk-containing compositions are also described in U.S. Pat. No. 3,985,901 (C. G. Barberan), IE65390 (Charleville Research Ltd), SU724113 (Kiev Bacterial Prep.) and SU 1,097,253 (Protsishin et al.), for example.
NL 7,413,373 (DSO Pharmachim) describes the preparation of a soya bean-based food composition comprising live lactic acid bacteria, the composition being spray-dried under a stream of hot air.
Likewise, J73008830 (Tokyo Yakult Seizo) describes the preparation of food compositions based on tomato or soya bean and comprising live bacteria or yeasts, the compositions being spray-dried under a stream of hot air.
When a culture of lactic acid bacteria is spray-dried, the sprayed culture is generally subjected to a stream of hot air having a temperature of the order of 100.degree. C. to 180.degree. C., depending on the devices. The drying temperature poses, nonetheless, a few problems. U.S. Pat. No. 3,985,901 (C. G. Barberan) shows indeed that a drying temperature on the order of 180.degree. C. to 300.degree. C. is capable of killing all the live organisms. These observations were also confirmed in EP298605 (Unilever: page 2, lines 43-48), and EP63438 (Scottish Milk Marke: page 1, lines 14-21).
To remedy the destructive influence of the drying temperature, the culture of lactic acid bacteria is generally mixed with protective agents such as vitamins, amino acids, proteins, sugars and/or fats, for example. Unfortunately, the influence of temperature still remains predominant. Only the lactic acid bacteria which are naturally resistant to high temperatures survive a spray-drying sufficiently to make the process economically attractive.
In all the preceding documents, one stream of product is subjected to the spray-drying. There is another way to proceed, which consists in spray-drying conjointly two streams; on one side, the food composition stream and on the other side, the probiotic lactic acid stream. This is the case for disclosures of French Pat. No. 712,791, Swiss Pat. No. 572 568 and U.S. Pat. No. 2,127,524. In these documents, the air inlet temperature never exceeds 100.degree. C., so that there is no problem of survival of the bacteria present.